758 SEC. 17. MINERALOGY, CRYSTALLOGRAPHY, ETC. 



3506. A number of Imitations of large and small Amulets, 

 Idols, Implements, &c. of archaeological and ethnological 

 importance. Compare the work of Professor H. Fischer, " Nephrit 

 und Jadeit." Dr. Adolph Ziegler, Freiburg, Baden. 



These imitations (of different materials according to the characters of the 

 imitated minerals) were prepared, on the suggestion of Prof. H. Fischer, 

 Director of the Ethnographical Museum of the University of Freiburg, and 

 were used partly to preserve for the ethnographical collection of the University 

 copies of the originals sent to Freiburg for exhibition, and partly for purposes 

 of exchange. Professor Fischer says, in his new work on Nephrite and Jade, 

 " I had in Freiburg, in Baden, the much-desired opportunity for the manu- 

 " facture of casts, as Dr. Ziegler, whose preparations in wax are deservedly 

 " valued in the studies of anatomy and the history of evolution, has succeeded 

 " so happily in the imitation in wax of the originals which I handed to him, 

 " even to the extent of copying the original colours so exactly that it is difficult 

 " to say, on looking at the two together, which is the original and which 

 " the imitation." 



A list of the different pieces is given with the imitations, containing references 

 to Professor Fischer's work. 



3507. Sohncke's Universal Model of the Raumgitter, 



made by Heckmann of Carlsruhe, for explaining the theory of the 

 structure of crystals. 



Appendages to the model : 



A key. 



12 elastic spiral threads. 



6 tin caps. Prof- Sohncke, Carlsruhe. 



3508. Model of Octahedral " Raumgitter." 



Prof. Sohncke, Carlsruhe. 



The universal model of the raumgitter has the object of bringing to view 

 the 14 possible different kinds of Raumgitter or point systems of the parallel- 

 epiped form. 



Its importance consists in the following points : 



(1.) According to Bravais the molecules of all crystals are arranged in a 

 Raumgitter. 



(2.) According to a theory of crystal structure, developed a short time ago by 

 the exhibitor, the molecules are arranged according to regular systems of points, 

 which latter are always composed of many Raumgitters placed in each other. 



From this one model all raumgitters can be derived; it is made so as to 

 be movable. The dimensions can be altered by drawing out eight edges, 

 after the manner of a telescope. Also, the globe must be divided in similar 

 proportion to the edges. 



For the purpose of altering the angles, each angle is provided with two 

 joints, by means of one of which it is possible to incline the four unlengthen- 

 able edges, which are now vertical. The four horizontal edges must previously 

 be placed parallel to each other. 



Elastic threads are sent which can be stretched between different globes to 

 show their lines of combination. The tin caps are used for indicating par- 

 ticular spheres. 



The fixed model shows the octahedral Raumgitter ; of course the movable 

 model can be brought to this form. 



3509. Case, containing 15 Models of the most impor- 

 tant Diamonds, made with Bohemian crystal glass. 



Dr. Th. Schuchardt, Gorlitz. 



